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Re: UPDATE: datatypes

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Mon, 17 Dec 2001 13:46:19 -0500
To: connolly@w3.org
Cc: www-archive@w3.org, fps@research.bell-labs.com, phayes@ai.uwf.edu, jjc@hplb.hpl.hp.com, Frank.van.Harmelen@cs.vu.nl, horrocks@cs.man.ac.uk, mdean@bbn.com, lynn.stein@olin.edup
Message-Id: <20011217134619R.pfps@research.bell-labs.com>
From: Dan Connolly <connolly@w3.org>
Subject: Re: UPDATE: datatypes
Date: 17 Dec 2001 11:35:57 -0600

> On Mon, 2001-12-17 at 11:19, Peter F. Patel-Schneider wrote:
> > 		Datatypes in SWOL
> > 
> > 	Peter F. Patel-Schneider
> > 	Bell Labs Research
> > 	(17 December 2001)
> > 
> > 
> > The semantics and syntax documents that I sent out contain a treatment of
> > datatypes that has the following features.
> > 
> > 1/ Local datatyping syntax (and verification) can be handled by XML Schema
> >    verification.  In particular,
> >    
> >    <Person rdf:about="John">
> >      <age xsi:type="xsd:int">10</age>
> >    </Person>
> > 
> >    results in the age of John being the integer 10.
> Where is the specification of that syntax?

XML Schema Part 1: Structures, http://www.w3.org/TR/xmlschema-0/, Section
2.6.1 xsi:type, is, I believe, the primary specification of that syntax.
The syntax is used extensively in the XML Schema documents, including XML
Schema Part 0: Primer, http://www.w3.org/TR/xmlschema-0/, and, XML Schema
Part 2: Datatypes, http://www.w3.org/TR/xmlschema-2/.

> It doesn't mean what you suggest it means when parsed as RDF.

I'm not saying that it does mean *anything* as parsed by a current RDF/XML
parsed.  I'm saying that it does mean something in

	``The semantics and syntax documents that I sent out''


> > 1/ Determine if you disagree with the following:
> >    - The above is a reasonable way of handling datatypes in SWOL.
> nope; it's very much more complex, syntacitcally and
> in the model theory, than other alternatives
> under discussion in the RDF Core WG.

Objection noted.

The proposal in my documents is more semantically complex than others
simply because it handles data values that do not have a locally-specified
lexical-to-value mapping.  If one were to move to an environment where this
mapping either had to be locally given for all literals or where the
mapping was unambiguous overal then there would be little difference in the
semantic complexity.

> >    - The above does not introduce other problems.
> > 
> > 2 (optional)/ Make suggestions for improvements.
> See Melnick's work in the RDF Core WG:
>  http://www-db.stanford.edu/~melnik/rdf/datatyping/

I take it that you are advocating datatyping scheme ``S''.  

I have serious reservations about ``S'', mostly concerning compatibility
with existing RDF usage and with XML documents.

If the RDF Core WG has not made a decision by the time of our face-to-face, 
it might be fruitful for us to spend some time on this issue there.


> -- 
> Dan Connolly, W3C http://www.w3.org/People/Connolly/

Received on Monday, 17 December 2001 13:47:08 UTC

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